Eck & Co <Köln>
| Carl Leibl an Louis Spohr in Kassel | Köln, Mittwoch 30. September 1835 | 1835093044 |
| Ignaz van Houtem an Louis Spohr in Kassel | Aachen, Mittwoch 22. April 1840 | 1840042247 |
| Ignaz van Houtem an Louis Spohr in Kassel | Aachen, Dienstag 28. April 1840 | 1840042847 |
| Carl Leibl an Louis Spohr in Kassel | Köln, Mittwoch 30. September 1835 | 1835093044 |
| Ignaz van Houtem an Louis Spohr in Kassel | Aachen, Mittwoch 22. April 1840 | 1840042247 |
| Ignaz van Houtem an Louis Spohr in Kassel | Aachen, Dienstag 28. April 1840 | 1840042847 |